Every time I do a surface pass on my 7m Screamer it back stalls then falls out of the sky. It never used to do this. I've checked the lines, changed the settings in many different ways and it's not fixed. Could anyone give me ideas. Thanks

Not sure if its how you use the kite when doing a surface pass or the tunement. Does it back stall when the kite is full power and sheet in all the way? (you need to try this in light winds on the beach) If its stalling here then your front bridals have stretched. Pulling some depower should sort it out temorarily. I have this issue with a 7 m Rebel.
Also, bridals can shrink if they are exposed to saltwater all the time and never rinsed. I found that after washing my north bridals that I got and extra 2 cm length on some and lots of sand came out. Just a thought.
Anyhow, we need to see a video to really see what you are talking about.
good luck

Just trim the depower a little down (shortening frontlines a bit), just like one always does in really light wind.

It will cure this tendency

What you experience is most likely the "front line stretch" that goes on over time with ALL kitelines, and we all experience, so because of the higher load on the frontlines they get stretched a bit longer over time, and you have to trim the depower a little down (or change rear line knots) in order to have the kite behave like you are used to.

Simply pull the depower a bit more, and your kite will work as it used to

I had this happen, out the bag perfectly tuned for unhooking without any backstalling / no pre depowering kite - 2 months later always having to depower to unhook - redid line lengths even tuned for not backstalling and don't fly quite the same as it did. I am convinced this kite stretched in some weird way - far more likely to be lines stretched tho normally.

I've depowered the lines as much as possible which is why i'm confused and I checked them to make sure they were all the same length. I appreciate all the suggestions and I will go out and adjust it more and see what is going on.

some bow kites love folding up and/or stalling when they lose power. Here are some things to consider:

1. Back line tension - like people mentioned above. Your front lines could have stretched a bit in which case you'd need to pull the depower trim more.
2. wind strength - strong winds are less likely to result in this stalling.
3. How fast you are going downwind for your surface passes: The faster and more aggressive you are about aiming downwind for the pass - the more likely the kite will stall.

If lines are good and your trimming for it then the wind is too light. If this is the case the only thing you can do is hook back as fast as possible and push the bar away, grab the chickenloop and push the bar away, or loop the kite but that does not all ways work. At least that is my experience with light wind passes.